<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<link  type="text/css" rel="stylesheet" href="css/bootstrap.css" >
</head>
<body>
	<div class="container">
		<div class="row">
		<div class="col-md-4 col-sm-6 col-xs-12">第一行</div>
		<div class="col-md-4 col-sm-6 col-xs-12">第二行</div>
		<div class="col-md-4 col-sm-6 col-xs-12">第三行</div>
		</div>
	</div>
</body>
</html>